Currently, the only batteries (rechargeable or non-rechargeable) commercially available with ZnMn chemistries are round bobbin cells. ZnMn chemistries are low cost and lightweight, are environmentally benign, and have a very long charge retention. Round bobbin cells have a positive electrode that is stamped or pressed into a cylindrical hollow pellet and seated into a can, and the negative electrode is a gel that is filled into the center void of the positive electrode.
The high internal resistance of low capacity round bobbin cells limits the currents (i.e., power) that they can deliver. In contrast, flat plate (electrode) cells can be scaled up to large sizes providing high currents and storage capacities.
CA 2 389 907 A1 relates to a method of producing flat plate electrodes in a small format that exhibit high current densities, higher utilization of the active materials, and better rechargeability. The method of forming the electrodes requires the active materials, binders, thickening agents, additives, and an alkaline electrolyte to form a paste that is applied to a current collector. CA 2 389 907 A1 provides is a flat plate rechargeable alkaline manganese dioxide-zinc cell.
What is needed are low cost, lightweight, environmentally friendly batteries that can be used, for example, for large power back-up systems, which are primarily currently served by lead acid and NiCd chemistries. Such batteries should exhibit improvements in, for example, current density, memory effect (i.e., capacity fade), shelf life, charge retention (e.g., at higher operation temperatures), and voltage level of discharge curve over known round bobbin and flat plate cells.